The present invention relates to a cross flow fan system which is utilized for air conditioners and various other types of air conditioning systems.
Example 1 of the conventional cross flow fan:
The cross flow fan used in a conventional air conditioner is equipped with a suction opening a for air and a discharge opening 2 as shown in FIG. 4, has a heat exchanger 5 and a cross flow fan 4 in the casing, and a tongue section 3 and a rear guider 6 for stabilizing the air flow. In a construction of a conventional cross flow fan such as this, in order to reduce the depth of the casing, the heat exchanger 5 is installed so that the lower end of the heat exchanger 5 is above the shaft of the fan.
With the above construction for a cross flow fan, the direction of the air flowing into the cross flow fan 4 is brought close to the vertical direction as shown by the actual line 9. The vortex flow above the part 7 where the rear guider 6 and the outer circumferential surface of the fan are closest becomes difficult to generate. On the other hand, air which does not flow into the cross flow fan 4 from the part 7 increase as shown by the broken line flows directly into the discharging direction along the rear guider 6, resulting in a deterioration of discharged air volume and in noise characteristic.
Example 2 of the conventional cross flow fan:
FIG. 6 is a structural diagram of a cross flow fan for a conventional air conditioner. As shown in FIG. 6, the conventional cross flow fan incorporates a cross flow fan 101 in a casing 103, and at a position close to the outer circumferential surface of the fan, a tongue section 102 is provided having the same cross section (which plays a role of dividing the suction side and discharge side) in an overall area in the direction of the shaft of the fan. Incidentally, 104 represents a discharge opening.
In this case, the discharge flow rate at both ends 104a of the fan shown in FIG. 7 is less than that of the middle section 104b of the same fan. There is a possibility of generating a reverse suction flow depending on the shape of the tongue section 102, causing instability in the discharge flow rate of the fan. Furthermore, if a load 105 such as a heat exchanger is provided on the suction side of the fan, there is a possibility to easily generate surging of the discharged air flow particularly in the low air volume range.
In order to solve the above mentioned problems, there has been an attempt to stabilize the discharged air flow at both ends 104a of the fan by providing from the side plate a protruding portion (projection) 108 as shown by oblique lines on both ends 104a of the discharge opening. By using this method, the discharge flow rate of both ends 104a of the fan increases, making it difficult for surging to occur. However, depending on the position where this projection 108 is to be provided or the shape thereof, detailed experiments become necessary and there was a possibility of reduced discharge flow rate in some cases.
Example 3 of the conventional cross flow fan:
As shown in FIG. 15, the conventional fan is provided with a suction opening 202 for taking in the open air at the front of the casing 201, a discharge opening 203 is provided thereunder, and a fan 204 is freely rotatably on a portion surrounded by a partition board 205 and a rear guider 201' in the air duct connected to the blow off opening 203 from the aforementioned suction opening 202.
The partition board 205 provided between the aforementioned suction opening 202 and the discharge opening 203 is intended to eliminate the short-circuit flow between the two openings and a blind patch is used for this purpose.
In addition, in the above example of the conventional cross flow fan, when the fan 204 is rotated in the direction indicated by the arrow, the air flow "a" is generated and sent out from the discharge opening 203. In this case, eccentric eddy "b" having its center inside the fan is generated in a portion where the partition board 205 and the fan 204 are close to each other, so that turbulent flow "c" is generated to flow around the eccentric eddy "b" and to cause pulsating current to be generated in the discharge air flow or to reduce the discharge air volume.
The magnitude and position of the eddy of accessory current generated secondarily depend on the shape and installed position of the partition board 205 and the number of revolutions of the fan and other factors. In order to maintain these factors under stabilized conditions, the eccentric eddy is stabilized at a fixed position by adjusting the number of revolutions of the fan so that the discharge air flow without pulsation can be obtained.
In such a case as above, it was extremely difficult to find an optimum shape and position for the partition board 205 according to the number of revolutions of the fan 204 and the load on the suction side.
Example 4 of the conventional cross flow fan:
As shown in FIG. 18(a) and FIG. 18(b), in the construction of the cross flow fan used conventionally for air conditioners and the like, an air flow direction control blade 305a is provided at the discharge opening formed between the rear guide 302 enclosing the fan 301 and the stabilizer 303 of the front panel 304. The control blade 305a is a flat board-like blade which does not curve in either direction. When an upward air discharge flow is desired, the air flow direction control blade 305a is maintained almost horizontally as shown in FIG. 18(a). Therefore, because a large space is formed between the inward upper surface of the air flow direction control blade 305a and the upward piece 303' in this case, the air flow "b" such as cold air or hot air is obtained from the discharge opening between the lower surface of the air flow direction control blade 305a and the extended upper surface of the rear guide 302 while the eddy like air flow "a'" is being generated in this space. In addition, when downward air flow is desired and the aforementioned air flow direction control blade 305a is set vertically as shown in FIG. 18(b), the air flow "b'1" generated above the circumference of the fan 301 collides with the air flow direction control blade 305a almost at a right angle because the air flow direction control blade 305a is flat. The air flow "b'1" is then blown downward by the internal pressure which is increases after collision.
In this case, as is apparent from the constructions shown in FIG. 18(a) and FIG. 18(b), when the air flow direction control blade 305a is set horizontally, the space formed by the aforementioned air flow direction control blade 305a and the upward pieces 303' of the stabilizer 303 becomes wider causing stagnation. Therefore, there is a possibility that sufficient air volume cannot be obtained at the discharge opening. Furthermore, when the aforementioned air flow direction control blade 305a is set vertically, the air flowing along the rear guide 302 collides with the aforementioned air flow direction control blade 305a almost at right angle. This collision causes the force for pushing the air flow downward to be diminished, and therefore there is also a possibility in this case that sufficient air volume cannot be obtained and that this arrangement is not effective.